Design, Architecture, Gardens, Southern California Living

Mosquito traps and repellents: Gear to take the bite out of summer

June 29, 2012 | 7:11
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The most lethal predator in the world is a female that lives only a few weeks, hunts by following plumes of carbon dioxide and thinks the smell of decaying bacteria is delicious. “Mosquitoes cause 1 to 2 million deaths a year,” said Ray Anandasankar, an assistant professor in UC Riverside's entomology department. “It's a human-finding guided missile.”

The 176 mosquito species in the U.S. are more of a pest than a lethal threat, but when it feels like every single one has congregated in your backyard to join you for dinner, the need for solutions remains great.

A bevy of new products purport to keep mosquitoes away without having to slather repellent on your skin. The designs come in different forms — fans, misters, lanterns and more — but ultimately they fall into two categories: traps and repellents. How do they work? More important, do they work?

Let's start with traps: The number of traps on the market has grown to include models with names such as SkeeterVac and Mosquito Magnet.

Many burn propane or butane to create carbon dioxide that's combined with other compounds to boost the attractiveness of the plume. Mosquitoes are drawn to this trail and are blown into traps by fans. Researchers have been testing some traps that use compounds that mimic ammonia, lactic acid and caproic acid — human skin scents attractive to mosquitoes.

Traps do work, but consumers should know that products' claims about their range of effectiveness (some say as much as an acre) are usually based on laboratory extrapolations, not the real world. For best results, you may need more than one trap.

The biggest drawback to traps is the cost, from $300 to $800. They also require regular maintenance and replacement of fuel tanks, and they may lose effectiveness in breezy conditions.

Which brings us to repellents — all those candles, lamps and other devices that purport to drive away mosquitoes. Many contain DEET, the nickname for diethyl toluamide, or use as their active ingredient a compound called picaridin, lemon eucalyptus oil or citronella oil, which is derived from lemongrass.

Thermacell has developed “appliances,” pictured here, devices similar in size to a large TV remote and equipped with a butane cartridge that vaporizes the mosquito repellent allethrin, a synthetic copy of an insecticide derived from chrysanthemum flowers. The repellent is not considered toxic to humans, and Thermacell says it creates a 15-by-15-foot barrier of protection. Price: $26 to $32. The company also has developed lanterns that work in the same fashion.

The Thermacell line gets a thumbs up from entomologist Joseph Conlon, spokesman for the American Mosquito Control Assn., a nonprofit composed of individuals and organizations focused on vector control.

Picaridin is widely used outside the U.S. It is odorless, is less likely to irritate the skin and doesn't damage clothing. But Conlon said DEET remains the gold standard of repellents, despite its drawbacks. DEET is a solvent and can damage clothing and plastics and irritate some people's skin.

The demand for so-called natural solutions explains the growth of products such as the new Terminix AllClear Mosquito Mister With Naturals, pictured here. It's a battery-powered device that looks like a traditional backyard lantern but it sends out a mist of a lemongrass solution touted as “100% all natural.” Price: about $80.

The most reliable method, mosquito control researchers said, is the push-pull approach. Pull the insects into traps, and rely on repellents to push away any remaining bugs.

Don't bother eating garlic or relying on marigolds, daisies, chrysanthemums or any other plants said to repel mosquitoes. Their essential oils volatilize too quickly to have much effect on a mosquito that has traveled far to feast on your blood.

Wearing light-colored, loose clothing, however, does offer some protection. Mosquitoes are attracted by lactic acid on the skin, so shower after exercising and choose your drinks carefully. Some studies in the Philippines and France have shown that beer drinkers smell better to mosquitoes.